A data packet of a wireless communication system often cannot be received correctly. To improve reliability of data transmission, An ARQ (Automatic Repeat Request, automatic repeat request) technology is provided in the prior art.
In the ARQ technology, an SW-ARQ (Stop and Wait ARQ, stop and wait automatic repeat request) technology and a GBN-ARQ (Go-Back-N ARQ, go-back-N automatic repeat request) technology are often used. In the SW-ARQ technology, when a receiving end returns a reception acknowledgment message (ACK) for a previous data packet, a transmitting end transmits a next data packet; and when the receiving end returns a reception negative acknowledgment message (NACK) for the previous data packet, the transmitting end retransmits the previous data packet. Therefore, by using this technology, a system resource is wasted in a process of waiting for ACK/NACK. In the GBN-ARQ technology, the transmitting end continuously transmits data packets in sequence; and when receiving NACK returned by the receiving end, the transmitting end stops transmitting a new data packet, retransmits a data packet that corresponds to the NACK, and retransmits, in sequence, data packets subsequent to the data packet that corresponds to the NACK. Compared with the SW-ARQ technology, by using the GBN-ARQ technology, a utilization ratio of a channel is improved.
During implementation of data retransmission by using GBN-ARQ, the inventor finds that the prior art has at least the following problems. A relay cooperation communications technology is more and more used in an existing communication system to improve a success ratio of data transmission; however, for GBN-ARQ, a solution of the relay cooperation communications technology is not used, and therefore, when data retransmission is performed by using the GBN-ARQ technology, a success ratio of data packet retransmission is relatively low.